There is an ongoing need for improved adhesives in applications for everyday life, such as for taping, fastening, or attaching objects together, as well as in high technology applications, such as for clean and secure handling of semiconductor wafers, attachment of fiber optic devices, assembly of micro-fabricated components, etc. A particular need in many such applications is for an adhesive that can readily attach to a contact surface and hold on to it with high force during use, yet can be readily detached from the contact surface and without leaving any residue or damaging the surface.
Recent scientific research has noted that geckos are exceptional in their ability to rapidly climb up smooth vertical surfaces, including even glass or smooth metal surfaces. The mechanism of toe adhesion to climbing surfaces used by geckos is attributed to the morphology of its unique toe hairs, called “seta”, as described in U.S. Pat. No. 7,011,723 issued Mar. 14, 2006, to R. Full et al. By mimicking the natural seta, artificial seta microstructures have been fabricated having the adhesion property of gecko setae for use as an adhesive, such as disclosed U.S. Pat. No. 6,872,439, issued Mar. 29, 2005, to R. Fearing et al. These fabricated microstructure adhesives are generally referred to as “biomimetic microstructure adhesives” (BMA). Various methods have also been developed to manipulate BMA adhesive structures for improved holding of a substrate to a support surface, such as described in U.S. Pat. No. 6,722,026, issued Apr. 20, 2004, to M. Lent, and in U.S. Published Application 2005/0148984 of Lindsay et al, published Jul. 7, 2005.
However, the prior methods of using BMA adhesive for holding an object to a surface have not addressed the problem of how to easily release the BMA adhesive from the surface through simple and convenient means. In particular, it would be desirable to use BMA adhesive to hold clothing, jewelry, eyeglasses, or other accessories in contact with human skin, yet be able to easily release the BMA adhesive pad from the skin without causing any discomfort or pain to the user.